A display panel, such as a liquid crystal display (LCD) panel comprises a pixel area, a plurality of data lines and gate lines connected to the pixel area. These data lines and gate lines are connected to a plurality of integrated circuit drivers, or driver ICs, as shown in FIG. 1. Each of the driver IC typically has a bond pad area having a plurality of electrically conductive pads (not shown) to allow a plurality of electrical conductors to be connected to the connectors at the pixel area, as shown in FIG. 2. Because the spacing, SI, between adjacent conductors at the IC side is much smaller than the spacing, SP, between adjacent connectors at the pixel area, a fan-out pattern is used to spread out the conductors from the IC side to the pixel area. In this fan-out pattern, the side conductors are always longer than the conductors in the middle portion of the pattern. For example, conductor A is shorter than conductor B, which is shorter than conductor C, and so on. If the conductors are made of the same material and have substantially the same thickness and width, then a longer conductor has more electrical resistance than a shorter one.
In order to reduce the differences in electrical resistance among the conductors in a fan-out pattern, different zigzag path patterns are used for the conductors in the middle portion, as shown in FIG. 3. In particular, Na et al. (U.S. Pat. No. 6,104,465) discloses a fan-out connector pattern having a straight portion and a serpentine portion, wherein the conductors in the straight portion is made of a different material from the conductors in the serpentine portion. Moreover, the conductors in the serpentine portions may have many different serpentine shapes, such as wavelike shapes and ridged shapes.
Kim (U.S. Pat. No. 5,499,131) discloses a fan-out pattern wherein each conductor has a narrow conductor portion connected to a wide conductor portion. By adjusting the length of the wide conductor portion, the electrical resistance can be reduced or increased so as to reduce the resistance differences among the conductors. Fujii et al. (U.S. Pat. No. 5,757,450) discloses a fan-out pattern wherein each conductor has a narrow conductor portion, a wide conductor portion and an inclined conductor portion having an intermediate width located between the narrow conductor portion and wide conductor portion.
When the number of data/gate lines to be driven by a driver IC is very large, it may not be feasible to vary the conductor width or to adjust the length to the wide conductor portion in order to reduce the resistance differences among the conductors in a fan-out pattern. Thus, it would be advantageous to use different zigzag paths in a fan-out pattern to reduce the resistance differences. As shown in FIG. 3, a zigzag path allows the pathlength of a conductor to be extended on both sides of a straight line. The extension is represented by a swath width in FIG. 3. For example, conductor A has a swath width WA due to the zigzag path extension, conductor B has swath width WB, conductors C, D and E have swath widths WC, WD and WE, respectively. In general, the pathlength of a zigzag path increases with the swath width. Thus, in order to reduce the resistance differences among the conductors, the zigzag swath width in the middle conductors is greater than the zigzag swath width in the side conductors in the fan-out pattern. As shown in FIG. 3, WA is greater than WC, which is greater than WD and WE. As such, the pathlength differences in the conductors can be reduced or substantially eliminated. However, as the number of conductor connecting a driver IC to a display area grows, the zigzag paths in a fan-out pattern having one fan-out section such as the pattern shown in FIG. 3 may not be sufficient to reduce the resistance differences effectively.
It is thus advantageous and desirable to provide a different fan-out pattern in order to increase the range of a zigzag pathlength.